Cooling of the power components of a frequency converter

ABSTRACT

Cooling arrangement for the power components ( 10 ) of a power transformer, in which is a cooler ( 12 ), which has a metal frame, to which the power components can be fitted, and cooling piping fitted inside the frame for removing thermal power from the power components by means of a flowing cooling medium, and a condenser ( 13 ) connected to the cooling piping, with which thermal power can be transferred out of the cooling piping. The cooler and the condenser have a shared metal frame ( 11 ), in which one part functions as the cooler part and the other part as the condenser part, and inside which is fitted the shared cooling piping of the cooler and the condenser for the flowing cooling medium.

FIELD OF TECHNOLOGY

The object of this invention is a power transformer, such as a frequencyconverter, a cooling arrangement for power components, in which is acooler, which has a metal frame, to which the power components can befitted, and cooling piping fitted inside the frame for removing thermalpower from the power components by means of a flowing cooling medium,and a condenser connected to the cooling piping, with which thermalpower can be transferred out of the cooling piping.

PRIOR ART

In conventional frequency converters semiconductor power components,such as IGBTs, are fitted to a cooling plate, which transfers thermalpower further e.g. by means of cooling piping and the cooling liquidflowing in it onwards to a condenser, in which the thermal power can betransferred from the cooling liquid into the air.

In air cooling solutions according to prior art the point-likedissipated power of a semiconductor component is dissipated only fromthe small area of the cooling plate close to the semiconductorcomponent, in which case cooling is relatively inefficient (FIG. 1).

SUMMARY OF THE INVENTION

The purpose of this invention is to achieve a new kind of coolingarrangement for the power components of a frequency converter.

According to the invention the cooler and the condenser have a sharedmetal frame, in which one half functions as a cooler and the other halfas a condenser, and inside which is fitted the shared cooling piping ofthe cooler and the condenser for the flowing cooling medium.

The frame can be formed from one piece or otherwise from a plurality offrame pieces that are joined together.

The cooling medium piping can contain channels provided with aturbulator (a turbulator is e.g. an additional part resembling a spiralspring, which achieves rotation of the liquid flow, i.e. turbulence, inthe channel which has an advantageous effect on heat transfer) forarranging enclosed liquid circulation between the ends. The coolingmedium can be a cooling liquid, which is circulated with a pump. It canalso be water under low pressure, which boils in the cooling part andliquefies in the condenser part (heating pipe), and in which theliquid/vapour circulation between the parts occurs without a pump. Anarray of fins can be connected to the condenser part for transferringthermal power into the air duct e.g. forced by a fan. A separate liquidelement can also be connected to the condenser part for transferringthermal power to an external liquid circulation.

The frame of the cooling appliance can simultaneously function as thewhole frame of the transformer appliance.

The characteristic features of the solution according to the inventionare described in detail in the claims below.

By means of the invention a very compact and efficient coolingarrangement for the power components of a frequency converter can beachieved. More particularly by means of the invention point-likedissipation power dissipates utilizing all the cooling surface area, inwhich case cooling efficiency is significantly improved.

SHORT DESCRIPTION OF THE DRAWINGS

In the following, the invention will be described in more detail by theaid of an embodiment with reference to the attached drawings, wherein

FIG. 1 presents the transfer of dissipation power to a prior-art aircooler.

FIG. 2 presents the transfer of dissipation power to an air cooleraccording to the invention.

FIG. 3 presents a perspective drawing of the cooling appliance of afrequency converter according to the invention, and

FIG. 4 presents another cooling appliance of a frequency converteraccording to the invention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 presents how the dissipated power transfers to the cooler in aprior-art air cooler 1. Dissipated power is generated in the powersemiconductor piece 3 contained in the power module 2, from where ittransfers inside the cooler as is well known at a certain angle towardsthe cooling fins. Thus only a certain part of the array of fins of thecooler functions effectively (shaded part 4).

FIG. 2 presents the principle of the cooling solution according to theinvention. In the figure a pipe 4 containing liquid is disposed in theshared metal frame 1 under the power module, which pipe transfers thedissipated power of the power semiconductor piece 3 to the condenserpart 5, of which the whole cooling surface area is utilized since theliquid pipe extends to the whole finned area.

FIG. 3 presents a practical embodiment of a cooling appliance of afrequency converter according to the invention for cooling the powercomponents 10 of the power stage, typically power semiconductorswitches, e.g. IGBTs. In the appliance the frame part of the coolingsolution is an integral right-angled metal part 11, in which are facesurfaces 111, of which semiconductor switches are situated on one, endsurfaces 112, and side surfaces 113, and in which one half functions asa cooler 12, with which the transfer of thermal power from the powercomponents to the liquid is achieved, and the other half as a condenser13, by means of which the transfer of thermal power from the liquid intothe air is achieved (so-called primary cooling), and inside which areparallel and longitudinal (see the arrow between the cooler part and thecondenser part) channels 15, provided with a turbulator 14, forarranging enclosed cooling liquid circulation between the ends, in whichcase a liquid circulation is achieved inside the cooler. In addition tothe channels, an expansion tank can be disposed e.g. at the end of thecondenser. The liquid can be water, which is circulated with a pump 16,which contains a frame part 17, which is connected at its side surfaceto the side of the metal frame 11 of the appliance.

The liquid can also be water under low pressure, which boils in thecooling part and liquefies by means of the heating pipes and the heatingappliance in the condenser part, and in which the liquid/vapourcirculation between the parts occurs without a pump. The liquid/vapourcirculation can also be implemented in another manner suited to thepurpose.

A metallic array of fins 17 is joined to one of the face surfaces or toboth face surfaces (top and bottom surfaces) of the condenser part 13for transferring dissipated power to the air duct under the force of thefan. Alternatively e.g. a separate liquid element can be connected tothe condenser part for transferring thermal power to an external liquidcirculation.

FIG. 4 presents another embodiment of a cooling appliance according tothe invention, which has two right-angled frame parts 21 and 31, onwhich are face surfaces 211, 311, end surfaces 212, 312 and sidesurfaces 213, 313, and in which the frame parts are joined tightlytogether at the end surface 212 of one part and at the face surface 311of the other part, and in both of which frame parts is cooling piping onthe inside such that when joined together they form an integral coolingpiping. IGBTs are arranged on the face surface of one frame part, whichfunctions as a cooler, and a cooling array of fins to the other facesurface of the other frame part, which can be comprised of two differentfin array parts 27, 37, and which thus functions as a condenser.

It is obvious to the person skilled in the art that the differentembodiments of the invention are not limited solely to the exampledescribed above, but that they may be varied within the scope of theclaims presented below. Also other condenser solutions (so-calledsecondary cooling) can be used instead of a cooling array of fins. Thesolution according to the invention enables variation of the secondarycooling appliance, depending on the application and the usage site, atthe latest possible stage, and no separate structures for secondarycooling are needed in the solution according to the invention.

1. Cooling arrangement for the power components (10) of a powertransformer, in which is a cooler (12), which has a metal frame, towhich the power components can be fitted, and cooling piping fittedinside the frame for removing thermal power from the power components bymeans of a flowing cooling medium, and a condenser (13) connected to thecooling piping, with which thermal power can be transferred out of thecooling piping, characterized in that the cooler and the condenser havea shared metal frame (11, 21, 31), in which one part functions as thecooler part and the other part as the condenser part, and inside whichis fitted the shared cooling piping of the cooler and the condenser forthe flowing cooling medium.
 2. Cooling arrangement according to claim 1,characterized in that the cooling medium is liquid and the coolingmedium piping contains channels for arranging enclosed liquidcirculation.
 3. Cooling arrangement according to claim 2, characterizedin that turbulators are arranged in the channels for improving heattransfer.
 4. Cooling arrangement according to claim 1, characterized inthat the cooling medium is a liquid, which is circulated with a pump. 5.Cooling arrangement according to claim 1, characterized in that thepiping contains heating pipes and the cooling medium is water under lowpressure, which can be made to boil in the cooling part and to liquefyin the condenser part.
 6. Cooling arrangement according to claim 1,characterized in that an array of fins is connected to the condenserpart for transferring thermal power into the air duct e.g. forced by afan.
 7. Cooling arrangement according to claim 1, characterized in thata separate liquid element is connected to the condenser part fortransferring thermal power to an external liquid circulation.
 8. Coolingarrangement according to claim 1, characterized in that the frame of thecooling arrangement is simultaneously the whole frame of the transformerappliance or a part of it.
 9. Cooling arrangement according to claim 1,characterized in that the frame is formed from two or more connectedframe parts, which are each joined to the facing surface of the other,and in which are cooling piping parts that are fitted to each other. 10.Cooling arrangement according to claim 1, characterized in that theframe is formed from one frame piece.
 11. Cooling arrangement accordingto claim 2, characterized in that an array of fins is connected to thecondenser part for transferring thermal power into the air duct e.g.forced by a fan.
 12. Cooling arrangement according to claim 3,characterized in that an array of fins is connected to the condenserpart for transferring thermal power into the air duct e.g. forced by afan.
 13. Cooling arrangement according to claim 4, characterized in thatan array of fins is connected to the condenser part for transferringthermal power into the air duct e.g. forced by a fan.
 14. Coolingarrangement according to claim 5, characterized in that an array of finsis connected to the condenser part for transferring thermal power intothe air duct e.g. forced by a fan.
 15. Cooling arrangement according toclaim 2, characterized in that a separate liquid element is connected tothe condenser part for transferring thermal power to an external liquidcirculation.
 16. Cooling arrangement according to claim 3, characterizedin that a separate liquid element is connected to the condenser part fortransferring thermal power to an external liquid circulation. 17.Cooling arrangement according to claim 4, characterized in that aseparate liquid element is connected to the condenser part fortransferring thermal power to an external liquid circulation. 18.Cooling arrangement according to claim 5, characterized in that aseparate liquid element is connected to the condenser part fortransferring thermal power to an external liquid circulation. 19.Cooling arrangement according to claim 2, characterized in that theframe of the cooling arrangement is simultaneously the whole frame ofthe transformer appliance or a part of it.
 20. Cooling arrangementaccording to claim 3, characterized in that the frame of the coolingarrangement is simultaneously the whole frame of the transformerappliance or a part of it.